Quasi-statically tilted head having offset reader/writer transducer pairs

ABSTRACT

Aspects of the present invention relates generally to apparatuses with transducer arrays having offset transducers. Various embodiments are particularly suited to tilting for tape dimensional instability compensation. Some embodiments include dual servo readers in a given array.

BACKGROUND

The present invention relates to data storage systems, and moreparticularly, this invention relates to modules having arrays of offsetreader/writer transducer pairs that are selectively tiltable relative toa magnetic medium, thereby enabling read while write capability.

In magnetic storage systems, data is read from and written onto magneticrecording media utilizing magnetic transducers. Data is written on themagnetic recording media by moving a magnetic recording transducer to aposition over the media where the data is to be stored. The magneticrecording transducer then generates a magnetic field, which encodes thedata into the magnetic media. Data is read from the media by similarlypositioning the magnetic read transducer and then sensing the magneticfield of the magnetic media. Read and write operations may beindependently synchronized with the movement of the media to ensure thatthe data can be read from and written to the desired location on themedia.

An important and continuing goal in the data storage industry is that ofincreasing the density of data stored on a medium. For tape storagesystems, that goal has led to increasing the track and linear bitdensity on recording tape, and decreasing the thickness of the magnetictape medium. However, the development of small footprint, higherperformance tape drive systems has created various problems in thedesign of a tape head assembly for use in such systems.

In a tape drive system, magnetic tape is moved over the surface of thetape head at high speed. Usually the tape head is designed to minimizethe spacing between the head and the tape. The spacing between themagnetic head and the magnetic tape is crucial and so goals in thesesystems are to have the recording gaps of the transducers, which are thesource of the magnetic recording flux in near contact with the tape toeffect writing sharp transitions, and to have the read elements in nearcontact with the tape to provide effective coupling of the magneticfield from the tape to the read elements.

The quantity of data stored on a magnetic tape may be increased byincreasing the number of data tracks across the tape. More tracks aremade possible by reducing feature sizes of the readers and writers, suchas by using thin-film fabrication techniques and MR sensors. However,for various reasons, the feature sizes of readers and writers cannot bearbitrarily reduced, and so factors such as lateral tape motiontransients and tape lateral expansion and contraction (e.g.,perpendicular to the direction of tape travel) must be balanced withreader/writer sizes that provide acceptable written tracks and readbacksignals. One issue limiting areal density is misregistration caused bytape lateral expansion and contraction. Tape width can vary by up toabout 0.1% due to expansion and contraction caused by changes inhumidity, tape tension, temperature, aging, etc. This is often referredto as tape dimensional instability (TDI).

If the tape is written in one environment and then read back in another,the TDI may prevent the spacing of the tracks on the tape from preciselymatching the spacing of the reading elements during readback. In currentproducts, the change in track spacing due to TDI is small compared tothe size of the written tracks and is part of the tracking budget thatis considered when designing a product. As the tape capacity increasesover time, tracks are becoming smaller and TDI is becoming anincreasingly larger portion of the tracking budget and this is alimiting factor for growing areal density.

BRIEF SUMMARY

An apparatus according to one embodiment includes at least two modules,each of the modules having: an array of transducers, the transducers ineach array being arranged in pairs, wherein an axis of the array oftransducers is defined between opposite ends thereof. A first transducerof each of the transducer pairs of the modules is offset from a secondof the transducers of the transducer pair in a direction parallel to theaxis of the associated array. The first transducers of the transducerpairs of the second module are about aligned with the second transducersof the transducer pairs of the first module in the intended direction oftape travel when the axes of the arrays are oriented at a nominal anglebetween 0.1° and about 10° relative to a line oriented perpendicular toan intended direction of tape travel thereacross. The first transducersof the transducer pairs of the first module are about aligned with thesecond transducers of the transducer pairs of the second module in theintended direction of tape travel when the arrays are oriented at thenominal angle.

An apparatus according to another embodiment includes at least twomodules, each of the modules having an array of transducers, thetransducers in each array being arranged in pairs each pair having areader and a writer. An axis of each array of transducers is definedbetween opposite ends thereof. The writer of each of the transducerpairs of a first of the modules is offset from the reader of thetransducer pair in a first direction parallel to the axes of the arrays.The writer of each of the transducer pairs of a second of the modules isoffset from the reader of transducer pair in a second direction that isopposite the first direction. The writers of the transducer pairs of thesecond module are about aligned with the readers of the transducer pairsof the first module in the intended direction of tape travel when theaxes of the arrays are oriented at a nominal angle between 0.1° andabout 10° relative to a line oriented perpendicular to an intendeddirection of tape travel thereacross. The writers of the transducerpairs of the first module are about aligned with the readers of thetransducer pairs of the second module in the intended direction of tapetravel when the arrays are oriented at the nominal angle.

Any of these embodiments may be implemented in a magnetic data storagesystem such as a tape drive system, which may include a magnetic head, adrive mechanism for passing a magnetic medium (e.g., recording tape)over the magnetic head, and a controller electrically coupled to themagnetic head.

Other aspects and embodiments of the present invention will becomeapparent from the following detailed description, which, when taken inconjunction with the drawings, illustrate by way of example theprinciples of the invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1A is a schematic diagram of a simplified tape drive systemaccording to one embodiment.

FIG. 1B is a schematic diagram of a tape cartridge according to oneembodiment.

FIG. 2 illustrates a side view of a flat-lapped, bi-directional,two-module magnetic tape head according to one embodiment.

FIG. 2A is a tape bearing surface view taken from Line 2A of FIG. 2.

FIG. 2B is a detailed view taken from Circle 2B of FIG. 2A.

FIG. 2C is a detailed view of a partial tape bearing surface of a pairof modules.

FIG. 3 is a partial tape bearing surface view of a magnetic head havinga write-read-write configuration.

FIG. 4 is a partial tape bearing surface view of a magnetic head havinga read-write-read configuration.

FIG. 5 is a side view of a magnetic tape head with three modulesaccording to one embodiment where the modules all generally lie alongabout parallel planes.

FIG. 6 is a side view of a magnetic tape head with three modules in atangent (angled) configuration.

FIG. 7 is a side view of a magnetic tape head with three modules in anoverwrap configuration.

FIGS. 8A-8C are partial top-down views of one module of a magnetic tapehead according to one embodiment.

FIGS. 9A-9C are partial top-down views of one module of a magnetic tapehead according to one embodiment.

FIG. 10A is a partial top-down view of an apparatus with two modulesaccording to one embodiment.

FIG. 10B is a detailed view of the embodiment shown in FIG. 10A, takenfrom inside circle 10B.

FIG. 10C is a detailed view of the embodiment shown in FIG. 10A, takenfrom inside circle 10B.

FIG. 10D is a diagram of the system having the apparatus of FIG. 10A.

FIG. 10E is a partial top-down view of an apparatus with two modulesaccording to one embodiment.

FIG. 10F is a partial top-down view of a system with multiple sets ofmodules according to one embodiment.

FIG. 11A is a partial side view of a servo reader transducer pairaccording to one embodiment.

FIG. 11B is a partial side view of a servo reader transducer pairaccording to one embodiment.

FIG. 12 is a partial top-down view of a system with pairs of servotransducers according to one embodiment.

DETAILED DESCRIPTION

The following description is made for the purpose of illustrating thegeneral principles of the present invention and is not meant to limitthe inventive concepts claimed herein. Further, particular featuresdescribed herein can be used in combination with other describedfeatures in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be giventheir broadest possible interpretation including meanings implied fromthe specification as well as meanings understood by those skilled in theart and/or as defined in dictionaries, treatises, etc.

It must also be noted that, as used in the specification and theappended claims, the singular forms “a,” “an” and “the” include pluralreferents unless otherwise specified.

The following description discloses several preferred embodiments ofmagnetic storage systems having arrays of offset reader/writertransducer pairs, as well as operation and/or component parts thereof.In various embodiments herein, the arrays of reader/writer transducerpairs may incorporate an offset between the transducers of each of thereader/writer transducer pairs along the axes of the arrays. Moreover,the offset reader/writer transducer pairs may be selectively tiltable,thereby enabling read while write capability despite potential changesin the dimensions and/or orientation of a tape being written to and/orhaving data read therefrom, as will be discussed in further detailbelow.

In one general embodiment, an apparatus includes at least two modules,each of the modules having: an array of transducers, the transducers ineach array being arranged in pairs, wherein an axis of the array oftransducers is defined between opposite ends thereof. The axis of thearray of transducers is oriented at a nominal angle relative to a lineoriented perpendicular to an intended direction of tape travelthereacross, the nominal angle being between 0.1° and about 10°. Theaxes of the arrays of the at least two modules are oriented aboutparallel to each other. A first transducer of each of the transducerpairs of a first of the modules is offset from a second of thetransducers of each of the transducer pairs of the first module in afirst direction parallel to the axes of the arrays. A first transducerof each of the transducer pairs of a second of the modules is offsetfrom a second of the transducers of each of the transducer pairs of thesecond module in a second direction that is opposite the firstdirection. The first transducers of the transducer pairs of the secondmodule are about aligned with the second transducers of the transducerpairs of the first module in the intended direction of tape travel, andthe first transducers of the transducer pairs of the first module areabout aligned with the second transducers of the transducer pairs of thesecond module in the intended direction of tape travel, when the arraysare oriented at the nominal angle.

In another general embodiment, an apparatus includes a magnetic tapehead having at least two modules, each of the modules having an array oftransducers, the transducers in each array being arranged in pairs. Alsoincluded are a drive mechanism for passing a magnetic medium over themodules, and a controller electrically coupled to the modules. An axisof each array of transducers is defined between opposite ends thereof.The axis of each array of transducers is oriented at a nominal anglerelative to a line oriented perpendicular to an intended direction oftape travel thereacross, the nominal angle being between 0.1° and about10°. The axes of the arrays are oriented about parallel to each other. Afirst transducer of each of the transducer pairs of a first of themodules is offset from a second of the transducers of each of thetransducer pairs of the first module in a first direction parallel tothe axes of the arrays. A first transducer of each of the transducerpairs of a second of the modules is offset from a second of thetransducers of each of the transducer pairs of the second module in asecond direction that is opposite the first direction. The firsttransducers of the transducer pairs of the second module are aboutaligned with the second transducers of the transducer pairs of the firstmodule in the intended direction of tape travel, and the firsttransducers of the transducer pairs of the first module are aboutaligned with the second transducers of the transducer pairs of thesecond module in the intended direction of tape travel, when the arraysare oriented at the nominal angle.

FIG. 1A illustrates a simplified tape drive 100 of a tape-based datastorage system, which may be employed in the context of the presentinvention. While one specific implementation of a tape drive is shown inFIG. 1A, it should be noted that the embodiments described herein may beimplemented in the context of any type of tape drive system.

As shown, a tape supply cartridge 120 and a take-up reel 121 areprovided to support a tape 122. One or more of the reels may form partof a removable cartridge and are not necessarily part of the system 100.The tape drive, such as that illustrated in FIG. 1A, may further includedrive motor(s) to drive the tape supply cartridge 120 and the take-upreel 121 to move the tape 122 over a tape head 126 of any type. Suchhead may include an array of readers, writers, or both.

Guides 125 guide the tape 122 across the tape head 126. Such tape head126 is in turn coupled to a controller 128 via a cable 130. Thecontroller 128, may be or include a processor and/or any logic forcontrolling any subsystem of the drive 100. For example, the controller128 typically controls head functions such as servo following, datawriting, data reading, etc. The controller 128 may operate under logicknown in the art, as well as any logic disclosed herein. The controller128 may be coupled to a memory 136 of any known type, which may storeinstructions executable by the controller 128. Moreover, the controller128 may be configured and/or programmable to perform or control some orall of the methodology presented herein. Thus, the controller may beconsidered configured to perform various operations by way of logicprogrammed into a chip; software, firmware, or other instructions beingavailable to a processor; etc. and combinations thereof.

The cable 130 may include read/write circuits to transmit data to thehead 126 to be recorded on the tape 122 and to receive data read by thehead 126 from the tape 122. An actuator 132 controls position of thehead 126 relative to the tape 122.

An interface 134 may also be provided for communication between the tapedrive 100 and a host (integral or external) to send and receive the dataand for controlling the operation of the tape drive 100 andcommunicating the status of the tape drive 100 to the host, all as willbe understood by those of skill in the art.

FIG. 1B illustrates an exemplary tape cartridge 150 according to oneembodiment. Such tape cartridge 150 may be used with a system such asthat shown in FIG. 1A. As shown, the tape cartridge 150 includes ahousing 152, a tape 122 in the housing 152, and a nonvolatile memory 156coupled to the housing 152. In some embodiments, the nonvolatile memory156 may be embedded inside the housing 152, as shown in FIG. 1B. In moreembodiments, the nonvolatile memory 156 may be attached to the inside oroutside of the housing 152 without modification of the housing 152. Forexample, the nonvolatile memory may be embedded in a self-adhesive label154. In one preferred embodiment, the nonvolatile memory 156 may be aFlash memory device, ROM device, etc., embedded into or coupled to theinside or outside of the tape cartridge 150. The nonvolatile memory isaccessible by the tape drive and the tape operating software (the driversoftware), and/or other device.

By way of example, FIG. 2 illustrates a side view of a flat-lapped,bi-directional, two-module magnetic tape head 200 which may beimplemented in the context of the present invention. As shown, the headincludes a pair of bases 202, each equipped with a module 204, and fixedat a small angle α with respect to each other. The bases may be“U-beams” that are adhesively coupled together. Each module 204 includesa substrate 204A and a closure 204B with a thin film portion, commonlyreferred to as a “gap” in which the readers and/or writers 206 areformed. In use, a tape 208 is moved over the modules 204 along a media(tape) bearing surface 209 in the manner shown for reading and writingdata on the tape 208 using the readers and writers. The wrap angle θ ofthe tape 208 at edges going onto and exiting the flat media supportsurfaces 209 are usually between about 0.1 degree and about 3 degrees.

The substrates 204A are typically constructed of a wear resistantmaterial, such as a ceramic. The closures 204B made of the same orsimilar ceramic as the substrates 204A.

The readers and writers may be arranged in a piggyback or mergedconfiguration. An illustrative piggybacked configuration comprises a(magnetically inductive) writer transducer on top of (or below) a(magnetically shielded) reader transducer (e.g., a magnetoresistivereader, etc.), wherein the poles of the writer and the shields of thereader are generally separated. An illustrative merged configurationcomprises one reader shield in the same physical layer as one writerpole (hence, “merged”). The readers and writers may also be arranged inan interleaved configuration. Alternatively, each array of channels maybe readers or writers only. Any of these arrays may contain one or moreservo track readers for reading servo data on the medium.

FIG. 2A illustrates the tape bearing surface 209 of one of the modules204 taken from Line 2A of FIG. 2. A representative tape 208 is shown indashed lines. The module 204 is preferably long enough to be able tosupport the tape as the head steps between data bands.

In this example, the tape 208 includes 4 to 22 data bands, e.g., with 8data bands and 9 servo tracks 210, as shown in FIG. 2A on a one-halfinch wide tape 208. The data bands are defined between servo tracks 210.Each data band may include a number of data tracks, for example 1024data tracks (not shown). During read/write operations, the readersand/or writers 206 are positioned to specific track positions within oneof the data bands. Outer readers, sometimes called servo readers, readthe servo tracks 210. The servo signals are in turn used to keep thereaders and/or writers 206 aligned with a particular set of tracksduring the read/write operations.

FIG. 2B depicts a plurality of readers and/or writers 206 formed in agap 218 on the module 204 in Circle 2B of FIG. 2A. As shown, the arrayof readers and writers 206 includes, for example, 16 writers 214, 16readers 216 and two servo readers 212, though the number of elements mayvary. Illustrative embodiments include 8, 16, 32, 40, and 64 activereaders and/or writers 206 per array, and alternatively interleaveddesigns having odd numbers of reader or writers such as 17, 25, 33, etc.An illustrative embodiment includes 32 readers per array and/or 32writers per array, where the actual number of transducer elements couldbe greater, e.g., 33, 34, etc. This allows the tape to travel moreslowly, thereby reducing speed-induced tracking and mechanicaldifficulties and/or execute fewer “wraps” to fill or read the tape.

While the readers and writers may be arranged in a piggybackconfiguration as shown in FIG. 2B, the readers 216 and writers 214 mayalso be arranged in an interleaved configuration. Alternatively, eacharray of readers and/or writers 206 may be readers or writers only, andthe arrays may contain one or more servo readers 212. As noted byconsidering FIGS. 2 and 2A-2B together, each module 204 may include acomplementary set of readers and/or writers 206 for such things asbi-directional reading and writing, read-while-write capability,backward compatibility, etc.

FIG. 2C shows a partial tape bearing surface view of complimentarymodules of a magnetic tape head 200 according to one embodiment. In thisembodiment, each module has a plurality of read/write (R/W) pairs 222 ina piggyback configuration formed on a common substrate 204A and anoptional electrically insulative layer 236. Although the writers(exemplified by the write transducer 214) and the readers (exemplifiedby the read transducer 216) are shown as being aligned parallel to anintended direction of travel of a tape medium thereacross, according toother embodiments, the write transducers 214 and the read transducers216 of each of the R/W pairs 222 may be offset in the plane ofdeposition thereof, as will be discussed in detail below (e.g., seeFIGS. 10A-10B).

It should be noted that the intended direction of tape travel issometimes referred to herein as the direction of tape travel, and suchterms may be used interchangeable. Such direction of tape travel may beinferred from the design of the system, e.g., by examining the guides;observing the actual direction of tape travel relative to the referencepoint; etc. Moreover, in a system operable for bi-direction readingand/or writing, the direction of tape travel in both directions istypically parallel and thus both directions may be considered equivalentto each other.

Several R/W pairs 222 may be present, such as 8, 16, 32 pairs, etc. TheR/W pairs 222 as shown are linearly aligned in a direction generallyperpendicular to a direction of tape travel thereacross. However, thepairs may also be aligned diagonally, etc. Servo readers 212 arepositioned on the outside of the array of R/W pairs, the function ofwhich is well known.

Furthermore, the servo readers 212 may include a pair of transducers(not shown) which are offset in the plane of deposition thereof.According to various embodiments, the offset between the transducers ofthe servo readers 212 may be determined using any of the embodimentsdescribed in detail below. Moreover, although the transducer pairs aredepicted as having common shields for each of the servo readers 212,according to other embodiments, each of the transducers may have theirrespective shields, e.g., as illustrated in FIG. 11B.

With continued reference to FIG. 2C, the magnetic tape medium generallymoves in either a forward or reverse direction along the intendeddirection of tape travel, as indicated by arrow 220. The magnetic tapemedium and head assembly 200 operate in a transducing relationship inthe manner well-known in the art. The piggybacked MR head assembly 200includes two thin-film modules 224 and 226 of generally identicalconstruction.

Modules 224 and 226 are joined together with a space present betweenclosures 204B thereof (partially shown) to form a single physical unitto provide read-while-write capability by activating the writer of theleading module and reader of the trailing module aligned with the writerof the leading module parallel to the direction of tape travel relativethereto. When a module 224, 226 of a piggyback head 200 is constructed,layers are formed in the gap 218 created above an electricallyconductive substrate 204A (partially shown), e.g., of AlTiC, ingenerally the following order for the R/W pairs 222: an insulating layer236, a first shield 232 typically of an iron alloy such as NiFe (−), CZTor Al—Fe—Si (Sendust), a sensor 234 for sensing a data track on amagnetic medium, a second shield 238 typically of a nickel-iron alloy(e.g., ˜80/20 at % NiFe, also known as permalloy), first and secondwriter pole tips 228, 230, and a coil (not shown). The sensor may be ofany known type, including those based on MR, GMR, AMR, tunnelingmagnetoresistance (TMR), etc.

The first and second writer poles 228, 230 may be fabricated from highmagnetic moment materials such as ˜45/55 NiFe. Note that these materialsare provided by way of example only, and other materials may be used.Additional layers such as insulation between the shields and/or poletips and an insulation layer surrounding the sensor may be present.Illustrative materials for the insulation include alumina and otheroxides, insulative polymers, etc.

The configuration of the tape head 126 according to one embodimentincludes multiple modules, preferably three or more. In awrite-read-write (W-R-W) head, outer modules for writing flank one ormore inner modules for reading. Referring to FIG. 3, depicting a W-R-Wconfiguration, the outer modules 252, 256 each include one or morearrays of writers 260. The inner module 254 of FIG. 3 includes one ormore arrays of readers 258 in a similar configuration. Variations of amulti-module head include a R-W-R head (FIG. 4), a R-R-W head, a W-W-Rhead, etc. In yet other variations, one or more of the modules may haveread/write pairs of transducers. Moreover, more than three modules maybe present. In further embodiments, two outer modules may flank two ormore inner modules, e.g., in a W-R-R-W, a R-W-W-R arrangement, etc. Forsimplicity, a W-R-W head is used primarily herein to exemplifyembodiments of the present invention. One skilled in the art apprisedwith the teachings herein will appreciate how permutations of thepresent invention would apply to configurations other than a W-R-Wconfiguration.

FIG. 5 illustrates a magnetic head 126 according to one embodiment ofthe present invention that includes first, second and third modules 302,304, 306 each having a tape bearing surface 308, 310, 312 respectively,which may be flat, contoured, etc. Note that while the term “tapebearing surface” appears to imply that the surface facing the tape 315is in physical contact with the tape bearing surface, this is notnecessarily the case. Rather, only a portion of the tape may be incontact with the tape bearing surface, constantly or intermittently,with other portions of the tape riding (or “flying”) above the tapebearing surface on a layer of air, sometimes referred to as an “airbearing”. The first module 302 will be referred to as the “leading”module as it is the first module encountered by the tape in a threemodule design for tape moving in the indicated direction. The thirdmodule 306 will be referred to as the “trailing” module. The trailingmodule follows the middle module and is the last module seen by the tapein a three module design. The leading and trailing modules 302, 306 arereferred to collectively as outer modules. Also note that the outermodules 302, 306 will alternate as leading modules, depending on thedirection of travel of the tape 315.

In one embodiment, the tape bearing surfaces 308, 310, 312 of the first,second and third modules 302, 304, 306 lie on about parallel planes(which is meant to include parallel and nearly parallel planes, e.g.,between parallel and tangential as in FIG. 6), and the tape bearingsurface 310 of the second module 304 is above the tape bearing surfaces308, 312 of the first and third modules 302, 306. As described below,this has the effect of creating the desired wrap angle α₂ of the taperelative to the tape bearing surface 310 of the second module 304.

Where the tape bearing surfaces 308, 310, 312 lie along parallel ornearly parallel yet offset planes, intuitively, the tape should peel offof the tape bearing surface 308 of the leading module 302. However, thevacuum created by the skiving edge 318 of the leading module 302 hasbeen found by experimentation to be sufficient to keep the tape adheredto the tape bearing surface 308 of the leading module 302. The trailingedge 320 of the leading module 302 (the end from which the tape leavesthe leading module 302) is the approximate reference point which definesthe wrap angle α₂ over the tape bearing surface 310 of the second module304. The tape stays in close proximity to the tape bearing surface untilclose to the trailing edge 320 of the leading module 302. Accordingly,read and/or write elements 322 may be located near the trailing edges ofthe outer modules 302, 306. These embodiments are particularly adaptedfor write-read-write applications.

A benefit of this and other embodiments described herein is that,because the outer modules 302, 306 are fixed at a determined offset fromthe second module 304, the inner wrap angle α₂ is fixed when the modules302, 304, 306 are coupled together or are otherwise fixed into a head.The inner wrap angle α₂ is approximately tan⁻¹ (δ/W) where δ is theheight difference between the planes of the tape bearing surfaces 308,310 and W is the width between the opposing ends of the tape bearingsurfaces 308, 310. An illustrative inner wrap angle α₂ is in a range ofabout 0.3° to about 1.1°, though can be any angle required by thedesign.

Beneficially, the inner wrap angle α₂ on the side of the module 304receiving the tape (leading edge) will be larger than the inner wrapangle as on the trailing edge, as the tape 315 rides above the trailingmodule 306. This difference is generally beneficial as a smaller α3tends to oppose what has heretofore been a steeper exiting effectivewrap angle.

Note that the tape bearing surfaces 308, 312 of the outer modules 302,306 are positioned to achieve a negative wrap angle at the trailing edge320 of the leading module 302. This is generally beneficial in helpingto reduce friction due to contact with the trailing edge 320, providedthat proper consideration is given to the location of the crowbar regionthat forms in the tape where it peels off the head. This negative wrapangle also reduces flutter and scrubbing damage to the elements on theleading module 302. Further, at the trailing module 306, the tape 315flies over the tape bearing surface 312 so there is virtually no wear onthe elements when tape is moving in this direction. Particularly, thetape 315 entrains air and so will not significantly ride on the tapebearing surface 312 of the third module 306 (some contact may occur).This is permissible, because the leading module 302 is writing while thetrailing module 306 is idle.

Writing and reading functions are performed by different modules at anygiven time. In one embodiment, the second module 304 includes aplurality of data and optional servo readers 331 and no writers. Thefirst and third modules 302, 306 include a plurality of writers 322 andno data readers, with the exception that the outer modules 302, 306 mayinclude optional servo readers. The servo readers may be used toposition the head during reading and/or writing operations. The servoreader(s) on each module are typically located towards the end of thearray of readers or writers.

By having only readers or side by side writers and servo readers in thegap between the substrate and closure, the gap length can besubstantially reduced. Typical heads have piggybacked readers andwriters, where the writer is formed above each reader. A typical gap is20-35 microns. However, irregularities on the tape may tend to droopinto the gap and create gap erosion. Thus, the smaller the gap is thebetter. The smaller gap enabled herein exhibits fewer wear relatedproblems.

In some embodiments, the second module 304 has a closure, while thefirst and third modules 302, 306 do not have a closure. Where there isno closure, preferably a hard coating is added to the module. Onepreferred coating is diamond-like carbon (DLC).

In the embodiment shown in FIG. 5, the first, second, and third modules302, 304, 306 each have a closure 332, 334, 336, which extends the tapebearing surface of the associated module, thereby effectivelypositioning the read/write elements away from the edge of the tapebearing surface. The closure 332 on the second module 304 can be aceramic closure of a type typically found on tape heads. The closures334, 336 of the first and third modules 302, 306, however, may beshorter than the closure 332 of the second module 304 as measuredparallel to a direction of tape travel over the respective module. Thisenables positioning the modules closer together. One way to produceshorter closures 334, 336 is to lap the standard ceramic closures of thesecond module 304 an additional amount. Another way is to plate ordeposit thin film closures above the elements during thin filmprocessing. For example, a thin film closure of a hard material such asSendust or nickel-iron alloy (e.g., 45/55) can be formed on the module.

With reduced-thickness ceramic or thin film closures 334, 336 or noclosures on the outer modules 302, 306, the write-to-read gap spacingcan be reduced to less than about 1 mm, e.g., about 0.75 mm, or 50% lessthan commonly-used LTO tape head spacing. The open space between themodules 302, 304, 306 can still be set to approximately 0.5 to 0.6 mm,which in some embodiments is ideal for stabilizing tape motion over thesecond module 304.

Depending on tape tension and stiffness, it may be desirable to anglethe tape bearing surfaces of the outer modules relative to the tapebearing surface of the second module. FIG. 6 illustrates an embodimentwhere the modules 302, 304, 306 are in a tangent or nearly tangent(angled) configuration. Particularly, the tape bearing surfaces of theouter modules 302, 306 are about parallel to the tape at the desiredwrap angle α₂ of the second module 304. In other words, the planes ofthe tape bearing surfaces 308, 312 of the outer modules 302, 306 areoriented at about the desired wrap angle α₂ of the tape 315 relative tothe second module 304. The tape will also pop off of the trailing module306 in this embodiment, thereby reducing wear on the elements in thetrailing module 306. These embodiments are particularly useful forwrite-read-write applications. Additional aspects of these embodimentsare similar to those given above.

Typically, the tape wrap angles may be set about midway between theembodiments shown in FIGS. 5 and 6.

FIG. 7 illustrates an embodiment where the modules 302, 304, 306 are inan overwrap configuration. Particularly, the tape bearing surfaces 308,312 of the outer modules 302, 306 are angled slightly more than the tape315 when set at the desired wrap angle α₂ relative to the second module304. In this embodiment, the tape does not pop off of the trailingmodule, allowing it to be used for writing or reading. Accordingly, theleading and middle modules can both perform reading and/or writingfunctions while the trailing module can read any just-written data.Thus, these embodiments are preferred for write-read-write,read-write-read, and write-write-read applications. In the latterembodiments, closures should be wider than the tape canopies forensuring read capability. The wider closures may require a widergap-to-gap separation. Therefore a preferred embodiment has awrite-read-write configuration, which may use shortened closures thatthus allow closer gap-to-gap separation.

Additional aspects of the embodiments shown in FIGS. 6 and 7 are similarto those given above.

A 32 channel version of a multi-module head 126 may use cables 350having leads on the same or smaller pitch as current 16 channelpiggyback LTO modules, or alternatively the connections on the modulemay be organ-keyboarded for a 50% reduction in cable span. Over-under,writing pair unshielded cables may be used for the writers, which mayhave integrated servo readers.

The outer wrap angles α₁ may be set in the drive, such as by guides ofany type known in the art, such as adjustable rollers, slides, etc. oralternatively by outriggers, which are integral to the head. Forexample, rollers having an offset axis may be used to set the wrapangles. The offset axis creates an orbital arc of rotation, allowingprecise alignment of the wrap angle α₁.

To assemble any of the embodiments described above, conventional u-beamassembly can be used. Accordingly, the mass of the resultant head may bemaintained or even reduced relative to heads of previous generations. Inother embodiments, the modules may be constructed as a unitary body.Those skilled in the art, armed with the present teachings, willappreciate that other known methods of manufacturing such heads may beadapted for use in constructing such heads.

As noted above, tape lateral expansion and contraction present manychallenges to increasing data track density on conventional products.Conventional products have attempted to compensate for tape lateralexpansion and contraction by controlling tape width by tension andimproving the characteristics of the media itself. However, thesemethods fail to fully cancel the tape lateral expansion and contraction,and actually lead to other problems, including tape stretching and mediacost increases, respectively.

FIGS. 8A-8C are intended to depict the effect of tape lateral expansionand contraction on transducer arrays position relative thereto, and arein no way intended to limit the invention. FIG. 8A depicts a module 800relative to the tape 802, where the tape has a nominal width. As shown,the transducers 804 are favorably aligned with the data tracks 806 onthe tape 802. However, FIG. 8B illustrates the effect of tape lateralcontraction. As shown, contraction of the tape causes the data tracks tocontract as well, and the outermost transducers 808 are positioned alongthe outer edges of the outer data tracks as a result. Moreover, FIG. 8Cdepicts the effect of tape lateral expansion. Here expansion of the tapecauses the data tracks to move farther apart, and the outermosttransducers 808 are positioned along the inner edges of the outer datatracks as a result. If the tape lateral contraction is greater than thatshown in FIG. 8B, or the tape lateral expansion is greater than thatshown in FIG. 8C, the outermost transducers 808 will cross onto adjacenttracks, thereby causing the adjacent tracks to be overwritten during awriting operation and/or resulting in readback of the wrong track duringa readback operation. Moreover, running effects, such as tape skew andlateral shifting may exacerbate such problems, particularly for tapehaving shingled data tracks.

Thus, it would be desirable to develop a tape drive apparatus able toread and/or write tracks onto the tape in the proper position,regardless of the extent of tape lateral expansion and/or contraction atany given time. Various embodiments described and/or suggested hereinovercome the foregoing challenges of conventional products, by orientingat least two modules of a tape drive apparatus, such as by rotating,pivoting and/or tilting, thereby selectively altering the pitch of thetransducers in their arrays, as will soon become apparent.

By selectively orienting a module, the pitch of the transducers on themodule is thereby altered, preferably aligning the transducers with thetracks on a tape for a given tape lateral expansion and/or contraction.Tape contraction (shrinkage) can be dealt with by orienting a nominallynon-offset head, but tape expansion (dilation) cannot. Thus, toaccommodate both shrinkage and dilation about a “nominal,” the head mustbe statically positioned at a nominal angle of at least approximately0.1° as will be explained below. Thereafter, smaller angular adjustments(e.g., about 1° or lower, but could be more) may be made to thealready-oriented module in order to compensate for any variation of thetape lateral expansion and/or contraction, thereby keeping thetransducers aligned with tracks on the tape.

FIGS. 9A-9C illustrate representational views of the effects oforienting a module having transducer arrays. It should be noted that theangles of orientation illustrated in FIGS. 9A-9C are an exaggeration(e.g., larger than would typically be observed), and are in no wayintended to limit the invention.

Referring to FIG. 9A, the module 900 is shown relative to the tape 902,where the tape has a nominal width. As illustrated, the module 900 isoriented at an angle θ_(nom) such that the transducers 904 are favorablyaligned with the data tracks 906 on the tape 902. However, when the tape902 experiences tape lateral contraction and/or expansion, the datatracks 906 on the tape contract and/or expand as well. As a result, thetransducers on the module are no longer favorably aligned with the datatracks 906 on the tape 902.

In FIG. 9B, the tape 902 has experienced tape lateral contraction.Therefore, in a manner exemplified by FIG. 8B, the transducers 904 onthe module 900 of FIG. 9B would no longer be favorably aligned with thedata tracks 906 on the tape 902 if no adjustment were made. However, asalluded to above, smaller angular adjustments may be made to thealready-oriented module 900 in order to compensate for tape lateralcontraction. Therefore, referring again to FIG. 9B, the angle oforientation >θ_(nom) of the module 900 is further positioned at an anglegreater than θ_(nom). By increasing the angle >θ_(nom) the effectivewidth w₂ of the array of transducers decreases from the effective widthw₁ illustrated in FIG. 9A. This also translates to a reduction in theeffective pitch between the transducers, thereby realigning thetransducers along the contracted data tracks 906 on the tape 902 asshown in FIG. 9B.

On the other hand, when the tape experiences tape lateral expansion, thedata tracks on the tape expand as well. As a result, the transducers onthe module would no longer be favorably aligned with the data tracks onthe tape if no adjustments were made. With reference to FIG. 9C, thetape 902 has experienced tape lateral expansion. As a result, furtherangular adjustments may be made to the angle of orientation of themodule in order to compensate for the tape lateral expansion. Therefore,referring again to FIG. 9C, the angle of orientation <θ_(nom) of themodule 900 is reduced to an angle less than θ_(nom). By decreasing theangle of orientation <θ_(nom) the effective width w₃ of the array oftransducers 904 increases from the effective width w₁ illustrated inFIG. 9A. Moreover, reducing the effective width of the array oftransducers 904 also causes the effective pitch between the transducersto be reduced, thereby realigning the transducers along the data tracks906 on the tape 902.

In a preferred embodiment, magnetic tape apparatuses have two or moremodules, each having an array of transducers, typically in a row.Depending on the desired embodiment, the additional rows of transducersmay allow the apparatus to read verify during the write process, but isnot limited thereto. As mentioned above, the foregoing conventionalchallenges may be overcome, e.g., by rotating a given module about anaxis orthogonal to the plane in which its array resides (e.g., parallelto the plane of the tape bearing surface), thereby selectively alteringthe pitch of the transducers in the array.

By providing an apparatus that compensates for tape lateral expansionand/or contraction, various embodiments enable use of wider readers,resulting in a better signal to noise ratio (SNR), and/or smaller datatracks, resulting in a higher capacity per unit area of the media.

Furthermore, a design having offset reader/writer transducer pairs maybe incorporated with any of the embodiments described herein, therebydesirably allowing read while write capability. Additional embodimentsdescribed herein preferably allow for offset servo readers to beincorporated in conjunction with the offset reader/writer transducerpairs. As alluded to above, this enables use of a standard servo band,thereby allowing placement of more tracks on the tape.

FIGS. 10A-10B depict an apparatus 1000 for compensating for tape lateralexpansion and/or contraction, in accordance with one embodiment. As anoption, the present apparatus 1000 may be implemented in conjunctionwith features from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however,apparatus 1000 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theapparatus 1000 presented herein may be used in any desired environment.Thus FIGS. 10A-10B (and the other FIGS.) should be deemed to include anyand all possible permutations.

Referring to FIGS. 10A-10B, the apparatus 1000 includes modules 1002,1004, each of which have an array 1006, 1008 of transducer pairs 1030.According to some embodiments, the apparatus 1000 may furtherincorporate a magnetic tape head, e.g., 200 of FIG. 2, the magnetic tapehead having the modules 1002, 1004, but is not limited thereto. Asmentioned above, although FIG. 2C illustrates the write transducers 214and the read transducers 216 of each of the R/W pairs 222 as beingaligned parallel to the intended direction 220 of tape travel, theoffset transducer pairs 1030 of the present embodiment may alternativelybe implemented in the magnetic tape head 200.

With continued reference to FIGS. 10A-10B, the transducer pairs 1030 ofeach of the modules 1002, 1004 include two transducers 1010, 1011.Furthermore, according to a preferred embodiment, one of the transducersin each of the pairs may be a reader, while the other of the transducersin each of the pairs may be a writer. Thus, the pairs 1010, 1011 oftransducers in each array may be reader/writer pairs.

In another embodiment, the modules 1002, 1004, may be fixed relative toeach other, e.g., to ensure a designed spacing therebetween during useof the apparatus 1000. In view of the present description, “fixed” isintended to mean constrained from a directional movement relative toeach other such that the arrays of each maintain a fixed positionrelative to each other. In other words, the modules may be fixed suchthat the axes 1012, 1013 of the arrays 1006, 1008 are oriented aboutparallel to each other, respectively.

It should be noted that the axes 1012, 1013 of each array 1006, 1008 oftransducer pairs 1030 are defined by the dashed lines that lie betweenopposite ends thereof, e.g., positioned farthest apart. According to apreferred embodiment, the axis 1012, 1013 of each of the at least onearray 1006, 1008 of transducers may be oriented about parallel to eachother, at a nominal angle φ relative to a line oriented perpendicular tothe intended direction 1020 of tape travel thereacross, as will bedescribed in further detail below.

In various embodiments, the modules may be fixed relative to each otherby using rods, fasteners, adhesives, cables, wire, etc. Moreover,according to different embodiments, the modules are preferably fixedrelative to each other prior to being installed in the apparatus 1000,head, etc. depending on the desired embodiment. However, the modules arepreferably selectively orientable (e.g., tiltable and/or rotatable) as asingle structure about a pivot point while remaining fixed relative toeach other, as will soon become apparent.

With continued reference to FIGS. 10A-10B, the transducers 1010, 1011within each of the transducer pairs 1030 are illustrated as being offsetfrom one another in a direction parallel to the axes 1012, 1013 of thearrays 1006, 1008. According to the illustrative embodiment depicted, afirst transducer 1010 of each of the transducer pairs 1030 of a first ofthe modules 1002 is offset Ω from a second transducer 1011 of each ofthe transducer pairs 1030 of the first module 1002 in a first directionparallel to the axes 1012, 1013 of the arrays 1006, 1008. Furthermore, afirst transducer 1010 of each of the transducer pairs 1030 the secondmodule 1004 is offset Ω from a second transducer 1011 of each of thetransducer pairs 1030 of the second module 1004 in a second directionthat is opposite (i.e., about antiparallel) the first direction.

According to various embodiments, the offset Ω between the transducers1010, 1011 in each of the transducer pairs 1030 for each of the arrays1006, 1008 may be at least approximately 3 μm (micrometers), but couldbe higher or lower depending on the desired embodiment. According topreferred embodiments, the offset Ω between transducers of each of thetransducer pairs 1030 of the first and second modules 1002, 1004 may beadjusted, e.g., such that transducers of opposing pairs are aboutaligned when the modules are oriented at about the nominal angle φ, aswill soon become apparent.

According to various embodiments, the nominal angle φ at which the axes1012, 1013 of the arrays 1006, 1008 are oriented may depend, at least inpart, on the offset Ω between transducers of each of the transducerpairs. According to preferred embodiments, the offset Ω betweentransducers of each of the transducer pairs 1030 of the first and secondmodules 1002, 1004 may be adjusted such that the first transducers 1010of the transducer pairs on the second module 1004 are about aligned withthe second transducers 1011 of the transducer pairs of the first module1002 in the intended direction 1020 of tape travel, when the axes 1012,1013 of the arrays 1006, 1008 are oriented at about the nominal angle φ,as illustrated in FIG. 10B. Furthermore, the first transducers 1010 ofthe transducer pairs of the first module 1002 are also preferably aboutaligned with the second transducers 1011 of the transducer pairs of thesecond module 1004 along imaginary line 1026 which is orientedsubstantially parallel to the intended direction 1020 of tape travel,when the axes 1012, 1013 of the arrays 1006, 1008 are oriented at aboutthe nominal angle φ, thereby enabling bidirectional read while writecapability for the apparatus 1000.

Moreover, looking to FIG. 10C, the transducer pairs 1030 of the modules1002, 1004 may also be oriented such that the second transducers 1011 ofthe transducer pairs on the second module 1004 are about aligned withthe second transducers 1011 of the transducer pairs of the first module1002 along imaginary line 1028 which is oriented substantially parallelto the intended direction 1020 of tape travel, when the axes 1012, 1013of the arrays 1006, 1008 are oriented orthogonal to the intendeddirection 1020, e.g., prior to being tilted to the desired nominal anglecp. Such a design also allows fabrication using a single module design,where the opposing modules are identical in construction.

Thus, a desired nominal angle φ value may be calculated and/ordetermined using the offset Ω (spacing) between the transducers 1010,1011 of the transducer pairs 1030, or vice versa. Furthermore, nominalangle φ values according to various offsets may be precalculated andstored in lookup tables, computer code, memory, etc., for future use.

In different embodiments, the nominal angle φ may be between about 0.05°and about 45°, more preferably between about 0.1° and about 10°,relative to a line 1022 oriented perpendicular to the direction 1020 oftape travel, but may be higher or lower depending on the desiredembodiment. Furthermore, the inventors have surprisingly andunexpectedly found that by incorporating a nominal angle φ in the rangebetween greater than about 0.1° and about 10° with various embodimentsdescribed herein, reading from and writing to the tape may be conductedwithout notably steering the tape and/or causing media damage over thelife of the tape. For example, the inventors expected that wrapping thetape over angled skiving edges would steer the tape laterally.

Angles of orientation greater than within the specified range (e.g.,greater than about 10°) are undesirable as higher angles tend to causesteering of the tape when used. However, as described above, the anglesof orientation within the specified range unexpectedly and unforeseeablydid not result in adverse steering of the tape. Moreover, it is moredifficult to distinguish between tape lateral expansion and/orcontraction and skew when angles of orientation of the modules aregreater than within the specified range. This may cause difficultieswhen matching the dimensional conditions of the tape and/or orientationof the modules of the current operation to that of the previousoperation (explained in further detail below). It should also be notedthat the angle of orientation φ illustrated in FIG. 10A is exaggerated(e.g., larger than within the desired range), and is in no way intendedto limit the invention.

Moreover, in FIG. 10A, each array 1006, 1008 is illustrated as includinga servo transducer 1032, 1034 respectively. According to a preferredembodiment, the center to center distance d₁, d₂ between each of theservo transducers 1032, 1034 and a data transducer 1010 of the nearesttransducer pair 1030 is preferably the same. However, in otherembodiments, the servo transducers 1032, 1034 may be spaced differentlyfrom the nearest data transducer, e.g., resulting in different valuesfor the respective distances d₁, d₂.

According to other embodiments, each array 1006, 1008 may include atleast one pair of servo transducers, where a given pair may bepositioned on one side of the array of transducers. Looking to theexemplary embodiment of a system 1200 depicted in FIG. 12, two arrays1006, 1008 of transducer pairs 1030 include pairs 1202, 1204 of servotransducers 1206 and 1208, 1210 and 1212 respectively. According to apreferred embodiment, each of the servo transducers are spacedsubstantially the same from a respective one of the transducers 1010 ofthe transducer pairs 1030 illustrated. In other words, the distance d₃between one of the servo transducers 1206 and a closer one of thetransducers 1010 of a transducer pair 1030 is substantially the same asthe distance d₄ between another one of the servo transducers 1208 and acloser one of the transducers 1010 of a transducer pair 1030.Additionally, the distance d₅ between one of the servo transducers 1210and a closer one of the transducers 1010 of a transducer pair 1030 issubstantially the same as the distance d₆ between another one of theservo transducers 1212 and a closer one of the transducers 1010 of atransducer pair 1030. In an exemplary embodiment, the distance d₃ isequal to the distance d₅, while the distance d₄ is equal to the distanced₆.

Moreover, the servo transducers 1206 and 1208, 1210 and 1212 of each ofthe pairs 1202, 1204 respectively, may have a spacing (offset)therebetween that is equal to the offset between the transducers in eachtransducer pair in the array 1006, 1008. Thus, the spacing between theeach of the pairs of servo transducers may be at least approximately 4micrometers, but could be higher or lower, depending on the desiredembodiment. However, in other embodiments, the spacing between the eachof the pairs of servo transducers may be different than the spacingbetween the transducers 1010, 1011 of the transducer pairs 1030.

Depending on the embodiment, the servo transducers in each of the pairof servo transducers may be coplanar, e.g., each of the servotransducers in a pair may be formed in the same deposition process offorming the servo transducers. Moreover, in a further embodiment, theservo transducers in each of the pairs of servo transducers may besubstantially aligned with the first transducers 1010 of the associatedarray, along the respective axes 1012, 1013 thereof. In other words, theservo readers are preferably in the same plane of deposition as the datareaders, and have a spacing within the pair of servo transducers equalto the offset between the first and second transducers 1010, 1011 (e.g.,the readers and writers) of the transducer pairs within the same array.

Depending on the embodiment, the servo readers may optionally becomprised of a common central hard bias magnet and may optionally havecommon magnetic shields (e.g., see FIG. 11A), but are not limitedthereto. Thus, in one embodiment, the servo transducers may share acommon longitudinal bias material, e.g., of a type known in the art.However, in other embodiments, the servo readers may be formed usingseparate hard bias magnets and/or magnetic shields, as will be describedin detail below (e.g., see FIG. 11B).

It follows that in some embodiments, the each of the modules 1002, 1004may have about identical construction. In other words, the modules 1002,1004 may have identical construction and design, except for processingvariations resulting during fabrication. One skilled in the art, uponbeing apprised of the present specification, will appreciate how toadapt known processes to perform the various steps listed herein.

The modules may originate from the same wafer. An advantage of suchco-fabrication is that the offsets between the reader/writer pairs arethe same for the two modules, thus producing more accurate trackplacement on tape. Referring to FIG. 10B, the offset Ω will be the sameon each module when the modules originate from the same wafer.

Moreover, a key advantage of having about identical construction is thatthe offset between transducers within each of the transducer pairs isbuilt into the wafer with a much higher degree of precision than ispossible with any conventional methods. Additionally, this enablesachieving high areal density while keeping the manufacturing costassociated with the various embodiments herein far less than those ofconventional products as the reader/writer pairs for either of thearrays of a given embodiment are formed from the same wafer.

During assembly of the apparatus, according to one embodiment, becausethe offset is built in at the wafer level, the modules are preferablyaligned without offset between readers on the opposing modules, forexample. See, e.g., the aligned readers in FIG. 12.

Referring now to FIG. 10D, the apparatus 1000 includes a mechanism 1014,such as a tape dimensional instability compensation mechanism, fororienting the modules to control a transducer pitch presented to a tape.The tape dimensional instability compensation mechanism 1014 preferablyallows for the orienting of the modules to be done while the modules arereading and/or writing. The tape dimensional instability compensationmechanism 1014 may be any known mechanism suitable for orienting themodules. Illustrative tape dimensional instability compensationmechanisms 1014 include worm screws, voice coil actuators, thermalactuators, piezoelectric actuators, etc.

A controller 1016 in one embodiment is configured to control the tapedimensional instability compensation mechanism 1014 based on a readbacksignal of the tape, e.g., servo signals, data signals, a combination ofboth, etc. Thus, in one embodiment, the controller 1016 may beconfigured to control the mechanism 1014 for orienting the modules basedon a skew of the tape. In another embodiment, the dimensional conditionsof the tape and/or orientation of the modules when the tape was writtenmay be retrieved e.g., from a database, cartridge memory, etc., and theorientation may be set based thereon to about match the transducer pitchof the current operation to that of the previous operation.

In various embodiments, additional logic, computer code, commands, etc.,or combinations thereof, may be used to control the tape dimensionalinstability compensation mechanism 1014 for adjusting the orientation ofthe modules based on a skew of the tape. Moreover, any of theembodiments described and/or suggested herein may be combined withvarious functional methods, depending on the desired embodiment.

FIG. 10E depicts a variation of an apparatus as shown in FIG. 10A, andlike elements are numbered the same in both FIGS. Referring again toFIG. 10E, it should be noted that the transducer pairs 1030 may includeany of the designs described above with reference to the transducerpairs 1010, 1011 of FIGS. 10A-10B.

According to the depicted embodiment, the apparatus 1000 includes aspacer member 1050 that extends between tape bearing surfaces of themodules. The spacer member 1050 may be recessed from a plane of the tapebearing surfaces, but is preferably coplanar therewith and/or otherwiseforms a portion of the overall tape bearing surface of the head.

In one embodiment, the spacer member 1050 includes a magnetic shield1052 for magnetically shielding the first array 1006 of transducer pairs1030 from the second array 1008 of transducer pairs 1030. Such magneticshield 1052 may be formed of any suitable material known in the art,such as NiFe, CoFe, etc.

According to one embodiment, the magnetic shield 1052 may extend fromthe tape bearing surface, or some point therebelow, in a heightdirection (into the tape bearing surface), preferably for a distancethat provides the desired shielding effect. For example, the shield 1052may have a height similar to that of shields of the transducers. Thus,the dimensions of the shield 1052 may be altered (e.g., tuned) dependingon the embodiment to achieve the desired effects for the overallfunctionality of the apparatus 1000.

FIG. 10F depicts an alternate embodiment of an apparatus 1040, similarto that of FIG. 10D, but having two sets 1042, 1044 of modules. Althougheach set 1042, 1044 is illustrated as having two modules 1002, 1004,according to other embodiments, each set 1042, 1044 may include at leasttwo modules, e.g., one or both of the sets may include more than twomodules. Moreover, each set 1042, 1044 of modules is preferablyindependently orientable, e.g., to set the angle of orientation.According to a further embodiment, each set of modules may also beindependently positionable for track following.

As illustrated, the sets 1042, 1044 of modules are coupled to acontroller 1016 as well as a mechanism 1014. According to preferredembodiments, the controller 1016 and/or the mechanism 1014 may be usedto position the two sets of modules, e.g., either uniformly, orindividually, depending on the desired embodiment. Moreover, thecontroller 1016 and/or the mechanism 1014 may include any of theembodiments described above with reference to FIG. 10C.

Referring still to FIG. 10F, according to one embodiment, the outermodules of each set 1042, 1044 of modules may be configured for writing,while the inner modules of each set 1042, 1044 may be configured forreading. Thus, in one illustrative use case, the writers on the outermodule of one set of modules may write while the readers of an innermodule of the second set of modules may read back the just-writtentrack. In another illustrative use case, the writers on the outer moduleof one set of modules may write while the readers of an inner module ofthe same set of modules may read back the just-written track.

Referring now to FIGS. 11A-11B, a servo reader 1100, having a transducerpair, is depicted in accordance with one embodiment. As an option, thepresent servo reader 1100 may be implemented in conjunction withfeatures from any other embodiment listed herein, such as thosedescribed with reference to the other FIGS. Of course, however, servoreader 1100 and others presented herein may be used in variousapplications and/or in permutations which may or may not be specificallydescribed in the illustrative embodiments listed herein. Further, theservo reader 1100 presented herein may be used in any desiredenvironment. Thus FIGS. 11A-11B (and the other FIGS.) should be deemedto include any and all possible permutations.

Looking to FIGS. 11A-11B, the servo reader 1100 includes a bottom shield1102 above which two sensor stacks are illustrated according to twodifferent designs as will soon become apparent. However, with continuedreference to both FIGS. 11A-11B, each of the sensor stacks have anantiferromagnetic (AFM) layer 1104, reference layer 1106, spacer layer1108, free layer 1110, cap layer 1112 and top shield 1114, as would beappreciated by one skilled in the art upon reading the presentdescription. The servo reader 1100 additionally includes an insulationlayer 1116 and a bias layer 1118, e.g., which may include anyconventional bias material of a type known in the art.

Referring now to FIG. 11A, the servo reader 1100 is shown as having acommon central bias layer 1118 as well as common magnetic bottom and topshield layers 1102, 1114 for the transducer pair. Yet, looking to FIG.11B, the servo reader 1100 is depicted as including separate shieldlayers 1102, 1114 and insulating layers 1116 for each of the transducersensor stacks, according to a different embodiment. Thus, depending onthe embodiment, a servo reader having a transducer pair may incorporatecommon or unique (e.g., individual) central bias layers, magnetic bottomshields and/or magnetic top shields.

It should also be noted that depending on the desired embodiment, theoffset offset shown in FIGS. 11A-11B may include a value according toany of the embodiments described above. However, according to apreferred embodiment, the offset offset between the sensor stacks ispreferably about the same as the offset between the transducers of thereader/writer pairs, e.g., see Ω of FIG. 10B. Furthermore, any of thelayers depicted in FIGS. 11A-11B may include conventional layers of atype known as would be appreciated by one skilled in the art uponreading the present description.

It will be clear that the various features of the foregoing systems,apparatuses, and/or methodologies may be combined in any way, creating aplurality of combinations from the descriptions presented above.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as “logic,” a “circuit,” “module,”“apparatus,” or “system.” Furthermore, aspects of the present inventionmay take the form of a computer program product embodied in one or morecomputer readable medium(s) having computer readable program codeembodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a non-transitory computer readable storage medium. A computerreadable storage medium may be, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, or device, or any suitable combinationof the foregoing. More specific examples (a non-exhaustive list) of thenon-transitory computer readable storage medium include the following: aportable computer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a portable compact disc read-only memory (e.g.,CD-ROM), a Blu-ray disc read-only memory (BD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a non-transitory computerreadable storage medium may be any tangible medium that is capable ofcontaining, or storing a program or application for use by or inconnection with an instruction execution system, apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a non-transitory computer readable storage medium and that cancommunicate, propagate, or transport a program for use by or inconnection with an instruction execution system, apparatus, or device,such as an electrical connection having one or more wires, an opticalfibre, etc.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fibre cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer, for example through the Internet using an Internet ServiceProvider (ISP).

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart(s) and/orblock diagram block or blocks.

It will be further appreciated that embodiments of the present inventionmay be provided in the form of a service deployed on behalf of acustomer.

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. Thus, the breadth and scope of an embodiment of the presentinvention should not be limited by any of the above-described exemplaryembodiments, but should be defined only in accordance with the followingclaims and their equivalents.

What is claimed is:
 1. An apparatus, comprising: at least two modules,each of the modules having: an array of transducers, the transducers ineach array being arranged in pairs, wherein an axis of the array oftransducers is defined between opposite ends thereof, wherein a firsttransducer of each of the transducer pairs of the modules is offset froma second of the transducers in the transducer pair in a directionparallel to the axis of the associated array, wherein the firsttransducers of the transducer pairs of the second module are aboutaligned with the second transducers of the transducer pairs of the firstmodule in the intended direction of tape travel when the axes of thearrays are oriented at a nominal angle between 0.1° and about 10°relative to a line oriented perpendicular to an intended direction oftape travel thereacross, and wherein the first transducers of thetransducer pairs of the first module are about aligned with the secondtransducers of the transducer pairs of the second module in the intendeddirection of tape travel when the axes of the arrays are oriented at thenominal angle.
 2. An apparatus as recited in claim 1, wherein the firsttransducers of the arrays are writers, wherein the second transducers ofthe arrays are readers.
 3. An apparatus as recited in claim 1, whereineach array further includes at least one pair of servo transducershaving a spacing therebetween that is equal to an offset between thetransducers in each transducer pair in the array.
 4. An apparatus asrecited in claim 3, wherein the servo transducers in the at least onepair of servo transducers are coplanar.
 5. An apparatus as recited inclaim 4, wherein the servo transducers in the at least one pair of servotransducers are substantially aligned with the first transducers of theassociated array along the axes of the arrays.
 6. An apparatus asrecited in claim 3, wherein the at least one pair of servo transducersshare a common longitudinal bias material.
 7. An apparatus as recited inclaim 3, wherein the at least one pair of servo transducers share acommon shield.
 8. An apparatus as recited in claim 1, comprising amechanism for orienting the modules to control a transducer pitchpresented to a tape.
 9. An apparatus as recited in claim 8, comprising acontroller configured to control the mechanism for orienting the modulesbased on a skew of the tape.
 10. An apparatus as recited in claim 1,wherein an offset between the transducers in each transducer pair in thearray is at least 3 μm.
 11. An apparatus as recited in claim 1, whereinthe modules have about identical construction.
 12. An apparatus asrecited in claim 1, comprising: a drive mechanism for passing a magneticmedium over the modules; and a controller electrically coupled to themodules.
 13. An apparatus, comprising: at least two modules, each of themodules having an array of transducers, the transducers in each arraybeing arranged in pairs, each pair having a reader and a writer; whereinan axis of each array of transducers is defined between opposite endsthereof, wherein the writer of each of the transducer pairs of a firstof the modules is offset from the reader of the transducer pair in afirst direction parallel to the axes of the arrays, wherein the writerof each of the transducer pairs of a second of the modules is offsetfrom the reader of the transducer pair in a second direction that isopposite the first direction, wherein the writers of the transducerpairs of the second module are about aligned with the readers of thetransducer pairs of the first module in the intended direction of tapetravel when the axes of the arrays are oriented at a nominal anglebetween 0.1° and about 10° relative to a line oriented perpendicular toan intended direction of tape travel thereacross, and wherein thewriters of the transducer pairs of the first module are about alignedwith the readers of the transducer pairs of the second module in theintended direction of tape travel when the arrays are oriented at thenominal angle.
 14. An apparatus as recited in claim 13, wherein eacharray further includes at least one pair of servo transducers having aspacing therebetween that is equal to an offset between the transducersin each transducer pair in the array.
 15. An apparatus as recited inclaim 14, wherein the servo transducers in the at least one pair ofservo transducers are coplanar.
 16. An apparatus as recited in claim 15,wherein the servo transducers in the at least one pair of servotransducers is substantially aligned with writers of the associatedarray along the axes of the arrays.
 17. An apparatus as recited in claim14, wherein the at least one pair of servo transducers share a commonlongitudinal bias material.
 18. An apparatus as recited in claim 14,wherein the at least one pair of servo transducers share a commonshield.
 19. An apparatus as recited in claim 13, comprising a mechanismfor orienting the modules to control a transducer pitch presented to atape.
 20. An apparatus as recited in claim 13, wherein the modules haveabout identical construction and originate from a same wafer.